Search

Heat is a major stressor during exercise, though its value in driving adaptation is not well understood. Muscle heating can upregulate pathways facilitating protein synthesis and could thereby enhance effects of exercise training, however, few studies have investigated this possibility. We examined whether heating active muscle during resistance training differentially affected physical and functional adaptations. Within a randomised contralateral-limb control study, ten healthy, resistance-untrained individuals (21 ± 3 y; 5 female) completed 30 sessions of progressive resistance training (12 weeks), performing 4 X 8 unilateral knee extensions at 70% of 1RM. One randomly-allocated thigh was heated during, and for 20 min after, each session using an electric pad eliciting muscle temperatures of >38 °C (HOT); the contralateral limb remained unheated (CON). Training intensity was progressed using 4-weekly strength assessments. Quadricep lean mass (measured using DXA) increased by 15 ± 7% in HOT (p = 0.00) and 15 ± 6% in CON (p = 0.00); the difference being trivial (p = 0.94). Peak isokinetic torque at 90°.s-1 increased by 30 ± 25% (HOT; p = 0.00) and 34 ± 33% (CON; p = 0.01), with no difference (p = 0.84) between limbs. Rate of torque development increased »40%, with no difference between limbs (p = 0.73). The increase in 3-RM strength was also similar in HOT (75 ± 16%) and CON (71 ± 14%; p = 0.80 for difference). No differences in mass or strength changes were evident between sexes. In conclusion, supplemental heating of active muscle during and after each bout of resistance training showed no clear positive (or negative) effect on training-induced hypertrophy or function. [ABSTRACT FROM AUTHOR]

Background: Heat is a major form of stress caused by exercise, though its value in driving adaptation is not well understood. Aim: Through a contralateral-limb control study we examined whether supplemental heating of active muscle during resistance training differentially affected physical and functional adaptations compared to those from traditional training without muscle heating. Methods: Ten healthy young adult volunteers (5 females) completed 12-wk progressive resistance training of the knee extensors, comprising 30 sessions of 32 repetitions (4 sets of 8) of unilateral knee extensions at 70% of legspecific 1-RM. One randomly allocated thigh was heated during and for 20 min after each training session, using a customised heat pad eliciting muscle temperatures of 38-39.5 °C. Thigh lean mass was measured at baseline and 12 weeks, and concentric knee extensor maximal isokinetic (90°.s-1) torque was measured at baseline and each 4 wk. Results: Quadriceps' lean mass increased across 12-wk training, by 15 ±7% (761 ±280 g; p=0.00) and 15 ±6% (752 ±304 g; p=0.00) in the heated and control limbs, respectively; the difference being trivial (0 ±3%; p=0.94). Peak torque increased (p=0.02) to more extent, by 33 ±38% and 35 ±37%, respectively; with an unclear difference of 2 ±17% between limbs (p=0.82). Rate of torque development increased by 47 ±44% in the heated limb (p=0.01) and 45 ±39% (p=0.08) in the control limb (difference: 2 ±18%; p=0.90). No sex differences were evident for mass or strength changes. Conclusions: Heating of the active muscle mass during and after resistance training shows no clear positive (or negative) effect on training-induced hypertrophy or the improvements in concentric isokinetic strength and rate of torque development, compared to those from resistance training without heat. [ABSTRACT FROM AUTHOR]